A prolonged seating posture of a wheelchair user may lead to the physical teardown of bodily functions, such as the lower extremities mobility, intestinal activity slowing down, as well as reduced and degraded blood circulation. In addition, seating poses the risk of bedsores. A stand-up wheelchair helps reduce these consequences by changing the body posture, as standing reduces the teardown of bodily functions. A stand-up wheelchair typically includes a tiltable seating surface that is installed with backrests and footrests onto a frame. The correct adjustment to the user's anatomical requirements is a very important criterion for the comfort which the wheelchair offers. The seat depth and lower leg ratio is determined based on the user's body dimensions. A stand-up chair is selected and manufactured from the standard program of a manufacturer according to the determined dimensions.
The user-specific manufactured stand-up chairs for small and large persons often lead with to an unsatisfactory comfort, since the standardized sizes of stand-up chairs are fitted to average body dimensions. Frequently, the adjustment shortcomings are only noticed indirectly by the user. Shearing movements between the body and the seating surface or an excessively strong knee pad superficial pressure may lead to the development of bedsores after a short utilization time.
Stand-up wheelchairs also offer the user the possibility of developing sports activities. For example, a handicapped person is able to play golf. In such a case it is particularly important that the wheelchair in the stand-up position offers high stability. So, for example, it is also a requirement that the footrest in the stand-up position rises from the ground on its supports. The backrest must stand parallel to the seating surface so it gives the golfer sufficient movement possibilities (torso rotation), in order to be able to produce a powerful swing.
In such a case, stand-up wheelchairs are often held ready and used by different users on the golf course. On people with an average size, custom fit stand-up wheelchairs cannot be used by handicapped people or only under significant comfort losses.
An aluminum adjustable stand-up wheelchair is described in CA 2 458 092. The seat depth can be changed with an adjustable backrest. Therefore the backrest is telescopically connected with the under frame of the seat. Telescopic tubes are not particularly functional in practical operation. In order to ensure stability, small tolerances are necessary. A frequent adjustment leads to deterioration. The telescopic tubes reciprocally arranged under the seating surface can tilt between each other. The backrest is then inclined against the seating surface and a safe straightening of the wheelchair is not possible. In addition, telescopic tubes are dirt susceptible, which is however unavoidable during sports activities.
What is needed, then, is a stand-up wheelchair that offers convenient adjustment to accommodate the user's size and activities.